During the yarn manufacturing process, yarn packages are formed by winding yarn onto yarn carriers which are rotating at high speeds, sometimes in excess of 8,000 rpms. Typically, a pick up groove is provided at one end of the tube for capturing the yarn and initiating the winding of the yarn on the tube. These yarn winding tubes are often made of paperboard or other fibrous materials such as that disclosed in U.S. Pat. Nos. 1,494,404 and 5,328,121.
The life of a laminated paper yarn tube is somewhat limited. Paper tubes are often damaged during shipment and/or winding of the yarn. Disfiguration of the tube may cause uneven rotation during yarn winding. Moisture absorption by the paper tube may also cause changes in dimension and other physical properties. Furthermore, paper tubes tend to create dust.
Plastic, re-usable winding tubes have been suggested as replacements for paper carriers. Examples of re-usable winding tubes are shown in U.S. Pat. Nos. 4,889,294 and 4,901,941.
One important feature of a yarn winding tube is the means for identification of the particular type of yarn on the tube without detailed inspection of the yarn. A visual symbol or identification mark is often applied to the rim of the tube, above the yarn which has been wound thereon. On paper tubes, these markings may be a printed symbol on the ends of the tube.
However, since the tubes are intended to be reused, an inventory of the marked tubes must be maintained for each particular type of yarn that is processed.